Active Material Coating Method for Secondary Battery and Coating Apparatus

ABSTRACT

A method of coating an active material for a secondary battery according to one embodiment of the present disclosure is a method of coating an active material on an electrode current collector of a secondary battery, the method comprising the steps of: disposing a guide member on each of the left and right sides based on a moving direction of the electrode current collector, and coating the active material onto the electrode current collector between the two guide members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.17/263,660, filed on Jan. 27, 2021, which is a national phase entryunder 35 U.S.C. § 371 of International Application No.PCT/KR2020/001011, filed on Jan. 21, 2020, which claims priority toKorean Patent Application No. 10-2019-0008260, filed on Jan. 22, 2019with the Korean Intellectual Property Office, the disclosures of whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a method and an apparatus for coatingan active material for a secondary battery, and more particularly, to amethod and an apparatus for coating an active material for a secondarybattery which prevents distortions at coating boundaries duringdouble-sided coating of an electrode current collector.

BACKGROUND ART

A secondary battery can be formed by inserting an electrode assemblycomposed of a positive electrode plate, a negative electrode plate and aseparator into a case and then sealing the electrode assembly. Each ofthe positive electrode plate or the negative electrode plate(hereinafter referred to as “electrode plate”) is produced by coatingactive material slurries onto a positive electrode conductive currentcollector or a negative electrode conductive current collector at afixed thickness, and an electrode assembly can be formed by interposinga separator between the both conductive current collectors, followed bywinding multiple times in a jelly-roll or cylindrical shape.

The electrode plate may be formed of an active material coated portionhaving the active material slurry coated thereon, and a non-coatedportion not having the active material slurry coated thereon. The activematerial coated portion is subjected to rolling to have an increasedadhesiveness with respect to an electrode current collector and toincrease the capacity density of the active material. The rolledelectrode plate may be dried and then cut into a predetermined sizeusing a cutter of a predetermined width, to be then used.

FIG. 1 is a view showing a conventional electrode current collector.FIG. 2 is a view showing a coating imbalance occurring duringdouble-sided coating of the electrode current collector.

Referring to FIG. 1 , a coated portion 15 on which an active materiallayer 20 formed by coating an active material onto an electrode currentcollector 10 is located, and a non-coated portion 16 wherein the activematerial is not coated onto the electrode current collector 10, areformed. However, a difference in coating loading level is generated bysurface tension in the process of coating the active material, whichcauses a problem that the thickness of the active material layer 20 isnot uniform. In other words, the end portion of the active materiallayer 20 corresponding to a boundary between the non-coated portion 16and the coated portion 15 is formed not vertically but is formed in adroplet shape, and thus, the active material layer 20 may have adifference in height as a whole. This difference in height can bealleviated in the rolling process, but it may be problematic duringdouble-sided coating of the electrode current collector describedhereinafter.

Referring to FIG. 2 , a first active material layer 20 a formed on onesurface of the electrode current collector 10 and a second activematerial layer 20 b formed on another surface are slightly changed inthe coating width due to surface tension when rolling occurs. Therefore,a gap may be formed at a distance between the respective active materiallayers from one side end of the electrode current collector 10. This gapmay increase the risk of ignition by contacting the active materials ofdifferent polarities with each other in the subsequent laminationprocess.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

It is an object of the present disclosure to provide a method and anapparatus for coating an active material for a secondary battery, whichprevents coating imbalance that may occur during double-sided coating ofan electrode current collector.

However, the problem to be solved by the embodiments of the presentdisclosure is not limited to the above-described problems, and can bevariously expanded within the scope of the technical idea included inthe present disclosure.

Technical Solution

According to one embodiment of the present disclosure, there is provideda method of coating an active material for a secondary battery in whichthe active material is coated onto an electrode current collector of asecondary battery, the method comprising the steps of: disposing a guidemember on each of the left and right sides based on a moving directionof the electrode current collector, and coating the active material ontothe electrode current collector between the two guide members.

The moving direction of the electrode current collector may move in alinear direction by a first roller rotating in a first rotatingdirection.

The method of coating an active material for a secondary battery furtherincludes a step in which the guide member is rotated and moved by asecond roller that rotates along a second rotating direction that is theopposite direction to the first rotating direction, wherein the secondroller may allow the guide member to rotate in place by a roller locatedat each of both ends of the guide member.

The method of coating an active material for a secondary battery mayfurther include a step in which a cleaner disposed in the guide membersucks a remaining active material of the guide member while the guidemember rotates.

Along with the movement of the electrode current collector and the guidemember and the suction of the cleaner, the guide member from which theremaining active material is removed may be redisposed in an area wherethe active material is not coated.

One side surface forming a boundary with the coated portion among bothside surfaces of the guide member may be perpendicular to an uppersurface of the electrode current collector.

By using the coating method described above, one surface of theelectrode current collector may be coated with the active material, andanother surface of the electrode current collector may be coated in thesame manner as in the method of coating one surface of the electrodecurrent collector with the active material.

The method of coating an active material for a secondary battery may,after the step of coating the active material onto the electrode currentcollector, further comprise a step of removing the guide member from theelectrode current collector, and a step of rolling the electrode currentcollector.

The guide member may be formed of one of a rubber belt and a cloth-basedbelt.

An area in which the guide member is disposed may correspond to anon-coated portion.

According to another embodiment of the present disclosure, there isprovided an apparatus for coating an active material for a secondarybattery, the apparatus comprising: a first roller for moving anelectrode current collector, a guide member disposed to correspond to anon-coated portion of the electrode current collector, a second rollerlocated respectively at both ends of the guide member to rotate theguide member in place, and a coating machine for coating the activematerial onto a coated portion of the electrode current collector,wherein the rotating direction of the first roller and the rotatingdirection of the second roller are opposite to each other.

The apparatus for coating an active material for a secondary batteryfurther includes a cleaner disposed in the guide member, wherein thecleaner can suck a remaining active material of the guide member.

One side surface forming a boundary with the coated portion among bothside surfaces of the guide member may be perpendicular to an uppersurface of the electrode current collector.

The guide member may be formed of one of a rubber belt and a cloth-basedbelt.

Advantageous Effects

According to the embodiments, by disposing a guide member on anelectrode currnt collector during the coating process, coating imbalancecan be prevented during double-sided coating of the electrode currentcollector.

In addition, since cleaning is performed while the guide member rotates,coating can be continuously performed without replacing the guidemember.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a conventional electrode current collector.

FIG. 2 is a view showing a coating imbalance occurring duringdouble-sided coating of an electrode current collector.

FIGS. 3 to 8 are views showing a method of coating an active materialfor a secondary battery according to one embodiment of the presentdisclosure.

FIG. 9 is a view showing an apparatus for coating an active material fora secondary battery according to another embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, various embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings so thatthose skilled in the art can easily implement them. The presentdisclosure may be modified in various different ways, and is not limitedto the embodiments set forth herein.

Parts that are irrelevant to the description will be omitted to clearlydescribe the present disclosure, and like reference numerals designatelike elements throughout the specification.

Further, in the drawings, the size and thickness of each element arearbitrarily illustrated for convenience of description, and the presentdisclosure is not necessarily limited to those illustrated in thedrawings. In the drawings, the thickness of layers, regions, etc. areexaggerated for clarity. In the drawings, for convenience ofdescription, the thicknesses of some layers and regions are exaggerated.

Further, throughout the specification, when a part is referred to as“including” a certain component, it means that it can further includeother components, without excluding the other components, unlessotherwise stated.

FIGS. 3 to 8 are views showing a method of coating an active materialfor a secondary battery according to one embodiment of the presentdisclosure.

Referring to FIG. 3 , a method of coating an active material for asecondary battery according to one embodiment of the present disclosureis a method of coating an active material on an electrode currentcollector of a secondary battery, the method comprising the step ofdisposing a guide member 50 on each of the left and right sides based ona moving direction of the electrode current collector 100. The electrodecurrent collector 100 may move in a linear direction by rotation of afirst roller 140. The electrode current collector 100 is notparticularly limited as long as it has high conductivity without causinga chemical change in an electrode for a secondary battery according tothe present embodiment. A fine unevenness may be formed on a surface ofthe electrode current collector 100 to increase the binding force of theactive material, and the electrode current collector 100 may havevarious shapes such as a film, a sheet, a foil, a net, a porous body, afoam body and a non-woven fabric.

The guide member 50 may be formed of one of a rubber belt and acloth-based belt. The guide member 50 allows the coated portion of theelectrode current collector 100 to be uniformly coated in the process ofcoating the active material in a subsequent process.

FIG. 4 shows a state in which the guide member 50 is disposed on bothside surfaces of the electrode current collector 100 before coating theactive material. Referring to FIG. 4 , one side surface 50 s forming aboundary with the coated portion among both side surfaces of the guidemember 50 may be perpendicular to an upper surface of the electrodecurrent collector 100. In other words, the two guide members 50 arepositioned to be spaced apart from each other, and the active materialmay be coated between the two guide members 50 in a process describedhereinafter. At this time, the side surface of the guide member 50forming a boundary with the coated portion 150 in which the activematerial is coated refers to a side surface of the guide member 50 whichis exposed to the side of the coated portion 150.

Referring to FIG. 5 , an electrode slurry is coated between two guidemembers 50 spaced apart from each other to form an active material layer200. The electrode slurry may include a mixture of an active material, aconductive material and a binder. In this case, referring to FIGS. 1 and5 , as a first roller 150 rotates in a first rotating direction, theelectrode slurry can be coated onto the coated portion 150, while theelectrode current collector 100 moves linearly in the direction of thearrow in FIG. 1 . In other words, the electrode slurry can becontinuously coated onto the electrode current collector 100 in adirection opposite to the arrow in FIG. 1 .

Referring to FIG. 6 , when the active material layer 200 is formed andthen dried, the guide member 50 may be removed. After removing the guidemember 50, an electrode for a secondary battery can be formed by passingthrough a rolling process.

FIG. 7 is a view showing an apparatus for coating an active material fora secondary battery including a cleaner. FIG. 8 is a cross-sectionalview taken along the cutting line X-Y of FIG. 7 .

Referring to FIGS. 7 and 8 , while including most of the embodimentsillustrated in FIGS. 3 to 6 , the following contents may be furtherincluded.

The method of coating an active material for a secondary batteryaccording to the present embodiment may further include a step in whichthe guide member 50 is rotated and moved by a second roller 250 thatrotates along a second rotating direction that is the opposite directionto the first rotating direction of the first roller 140 shown in FIG. 3. In this case, the second roller 250 may allow the guide member 50 torotate in place by a roller located respectively at both ends of theguide member 50. Here, the both ends of the guide member 50 indicateboth ends of the guide member 50 spaced apart from each other along themoving direction of the electrode current collector 100.

Further, according to the present embodiment, the method may furtherinclude a step in which a cleaner 300 disposed in the guide member 50sucks a remaining active material of the guide member 50 while the guidemember 50 rotates. Along with the movement of the electrode currentcollector 100 and the guide member 50 and the suction of the cleaner300, the guide member 50 from which remaining active materials areremoved may be redisposed in an area of a non-coated portion where theactive material is not coated. In other words, when the active materialis coated between two guide members 50 by using an active materialcoating machine 400 shown in FIG. 9 to be described later in a statewhere the guide member 50 is disposed, a portion of the active materialsremains on the guide member 50 as well. When such remaining activematerials are sucked through the cleaner 300 and the guide member 50 isredisposed on the electrode current collector 100 through the rotationalmovement, the guide member 50 can be continuously used withoutreplacement, and therefore, the process efficiency can be improved.

Referring to FIG. 8 , if a rotation speed along the second rotatingdirection of the second roller 250 conforms to a rotation speed alongthe first rotating direction of the first roller 150 in FIG. 3 , theguide member 50 can rotate in place even though the electrode currentcollector 100 moves linearly along the direction of the arrow in FIG. 8.

One surface of the electrode current collector 100 can be coated with anactive material by using the coating method described above, and thenthe other surface of the electrode current collector 100 can also becoated in the same manner as in the coating method described above. Inthis case, the guide member 50 is used to clarify a coating area and toreduce a difference in distortion occurring on both side surfaces of theelectrode current collector 100 according to an end shape generated by asurface tension, whereby the risk of ignition can be reduced. Inparticular, if there is no guide member as in the present embodiment,the coated end portion may be distorted for various reasons. Accordingto the present embodiment, the guide member 50 can reduce an error dueto surface tension and minimize a difference in two-stage coating of theupper and lower surfaces of the electrode current collector 100.

FIG. 9 is a view showing an apparatus for coating an active material fora secondary battery according to another embodiment of the presentdisclosure.

The apparatus for coating an active material for a secondary batteryaccording to the present embodiment may be an exemplary means forperforming the method of coating an active material for a secondarybattery as described above. Referring to FIGS. 3 to 8 described aboveand FIG. 9 , the apparatus for coating an active material for asecondary battery according to the present embodiment comprises: a firstroller 140 for moving an electrode current collector 100, a guide member50 disposed to correspond to a non-coated portion 160 of the electrodecurrent collector 100, a second roller 250 located respectively at bothends of the guide member 50 to rotate the guide member 50 in place, anda coating machine 400 for coating the active material onto the coatedportion 150 of the electrode current collector 100. In this case, therotating direction of the first roller 140 and the rotating direction ofthe second roller 250 are opposite to each other. The coating machine400 may be provided with a coating injection port 410 for injecting anactive material onto the electrode current collector 100.

The coating apparatus according to the present embodiment furtherincludes a cleaner 300 disposed in the guide member 50, wherein thecleaner 300 can suck the remaining active material of the guide member50. One side surface forming a boundary with the coated portion 150among both side surfaces of the guide member 50 may be perpendicular toan upper surface of the electrode current collector 100.

Although the preferred embodiments of the present disclosure have beendescribed in detail above, the scope of the present disclosure is notlimited thereto, and various modifications and improvements of thoseskilled in the art using the basic concepts of the present disclosuredefined in the following claims also belong to the scope of rights.

1. An apparatus for coating an active material for a secondary battery,the apparatus comprising: a first roller adapted to move an electrodecurrent collector, a guide member disposed to correspond to a non-coatedportion of the electrode current collector, a second roller locatedrespectively at both ends of the guide member configured to rotate theguide member in place, and a coating machine adapted to coat the activematerial on a coated portion of the electrode current collector, whereina rotating direction of the first roller and a rotating direction of thesecond roller are opposite to each other.
 2. The apparatus for coatingan active material for a secondary battery according to claim 1, furthercomprising a cleaner disposed in the guide member, wherein cleaner isconfigured to suction remaining active materials of the guide member. 3.The apparatus for coating an active material for a secondary batteryaccording to claim 2, wherein the cleaner suctions the remaining activematerials of the guide member while the guide member rotates.
 4. Theapparatus for coating an active material for a secondary batteryaccording to claim 1, wherein a one side surface forming a boundary withthe coated portion among both side surfaces of the guide member isperpendicular to an upper surface of the electrode current collector. 5.The apparatus for coating an active material for a secondary batteryaccording to claim 1, wherein the guide member is formed of one of arubber belt and a cloth-based belt.
 6. The apparatus for coating anactive material for a secondary battery according to claim 1, whereinone side surface forming a boundary with a coated portion among bothside surfaces of the guide member is perpendicular to an upper surfaceof the electrode current collector.
 7. The apparatus for coating anactive material for a secondary battery according to claim 1, wherein anarea in which the guide member is disposed corresponds to a non-coatedportion.